11.20 : 4 = 2.8 Because when you want to calculate how much money you pay for the number of gallons of gas, you have to take a price of something multiply the number of gallons. Similarly, when you want to find the price of a gallon of gas, you have to take the total cost divided by number of gallons of gas you buy.
The value closest to zero on the number line is greatest because all of the values are negative which is less than zero. -270 is closer to 0 than the other values.